Sound recording apparatus



Nov. 11, 1941. M. M. GRUBER SOUND RECORDING APPARATUS Filed Dec. 17,1938 3 Sheets-Sheet l m w P a m. Wm M ATTORN EY Nov. 11, 1941. M. M.GRUBER 2,262,732

SOUND RECORDING APPARATUS Filed D80. 17, 1938 5 Sheets-Sheet 2 INVENTORfi/OFF/J M 63055,?

' BY I ATTORNEY Patented Nov. 11, 1941 2,262,732 somvn nacoannvcAPPARATUS Morris M. Gruber, New York, N. Y., assignor to PrestoRecording Corporation, New York, N. Y., a corporation of New YorkApplication December 17, 1938, Serial No. 246,305

17 Claims.

This invention relates to sound recording apparatus, and morparticularly to the provision in such apparatus of mechanism forproducing a terminal or finishing track, or any high pitch spiralgroove.

The primary object of my invention is to generally improve soundrecording apparatus, and more especially, sound recording apparatus ofthe so-called instantaneous play-back type.

Machines which record sound on disc records for instantaneous play-backare already known. The records may be made of metal, but the better andmore popular type of record now in use is the so-called acetate disc.The sound track cut on such a disc is exceedingly fine, and a largenumber of lines may be recorded per inch, thus making possiblelong-playing records.

Th pick-up and pick-up arm used with such records is light in weight andfreely oscillatable. A pick-up arm for play-back is commonly provideddirectly on the recording apparatus. When the play-back is finished andwhile the pick-up needle is running in one of the few extra groovescommonly provided at the end of the recording, the pick-up arm is liftedfrom the record and replaced on its support.

Difliculty arises if the operator is not attentive or is busy with'othermatters, so that the pickup is not lifted promptly from the record. Whenthe needle reaches the end of the track, it usually swings rapidlyinwardly and then strikes the driving pins near the center of therecord, whereupon it rebounds outwardly and may cross the sound groovesat the inner part of the record, thereby spoiling a part of the record.To.

overcome this diiiiculty, a specialfinishing track may be provided atthe end of the record. This is preferably an extra-deep circular trackconcentrically related to the record. It is convenlent to make thistrack of uniform small diameter on all records, and to use a spiralrun-out groove of very large pitch which moves the reproducing stylusrapidly but safely inwardly from the end of the recording to theextra-deep circular groove at the center of the record.

The records produced on the recording apparatus may be played back onordinary phonographs. These are commonly equipped with with run-outgrooves.

ideally suited to promptly and positively tripsuch automatic stoppingmechanisms.

In instantaneous recording apparatus the lead screw is oftenappropriately mounted for ready removal and replacement, thus making itconveniently possible to change the pitch of the sound track, and thedirection of recording. By direction I mean whether th disc is cut fromthe outside in, or from the inside out, the latter procedure beingpreferred by many. The better grade machines are frequently suppliedwith a series of lead screws of different pitch and direction. Theobject of my invention is to provide spiralling mechanism of thecharacter already outlined, which mechanism further affords readyremoval and replacement of .the lead screw.

I am aware, of course, that standard commercially manufactured recordswhich are pressed from a master plate have been provided However, therecording machines used in that field are not provided with multiple andreadily interchangeable lead screws.

Further objects are to provide spiralling mechanism which is simple andinexpensive; which may be manually operated at any point on the record;which may therefore be used not only to provide a spiral run-out groove,but also a spiral starting groove and spiral connecting grooves betweenshort recordings, as for spot announcements, sound efl'ects,'etc.; andwhich may also be used to increase the sound track spacing or pitch at aparticular point in a record where the sound being recorded is ofunusually great amplitude.

To the accomplishment of the foregoing and such other objects as mayhereinafter appear, my invention consists in the recording andspiralling elements and their relation one to the other, as hereinafterare more particularly described in the specification and sought to bedefined in the claims.

Th specification is accompanied by drawings in which:

automatic stopping mechanism whichiatrippegm in response to a rapidinward movement of the pick-up arm or by movement of the pick-up armto aposition corresponding to minimum record groove diameter. The specialrun-out groove which is provided on the disc by my invention is 56 Fig.1 shows the major part of the recording apparatus in plan;

Fig. 2 is a transverse section drawn to enlarged scale and taken in theplane of the line 2-2 or m. 1;

Fig. 3 is a fragmentary horizontal section taken in the plane of theline 3-4 of Fig. 2:

Fig. 4 is a transverse section taken in the plane of the line 4-4 ofFla. 1; Fig. 5 is a transverse section taken in theplane of the line 5-4of Fig. 1;

Fig. 6 schematically illustrates a record provided with a spiralstarting groove as well as a g run-out groove; and

Fig. 7 schematically illustrates a record hav- 3 ceptfor .the startinglever 14; The cutting head 1 I (see Fig.4) is carried by a cutting headcarrier-IIHFigs. 1 and 4) which moves along a lead screw I8. rier armgenerally designated 20, said arm comprising end pieces 22 and 24rigidly connected and properlyspaced apart by tie rods 26. In thepresent case there are two such rods in superposed relation, as is bestshown in Figs. 2, 4 and 5.

At its inner end the carrier arm 20 is pro- 'vided' with a drivingflange 30 (Figs. 1, 2v and 3).

The flange 30'is provided with holes 32 which receive'driving'studsonthetumtable in order to insure synchronous rotation. It will beunderstood that the turntable carries the conventional centering pin,and that the record disc 34 has a center hole for the centering pin andthree additional holes for the driving studs.

Flange 30 is secured atthe lower end of an upright shaft 36' (Fig. 2),said shalt carrying a worm v38 which meshes with a worm gear 40. Theworm gear drives thelead screw I8.

In accordance with the present invention, this drive, instead of beingdirect, takes place through a suitable overrunning clutch. Specifically,and referring to Figs. 2 and 3, in the present example of theinvention,the worm geanll has a housing 42 secured thereto, said housingcarrying a pawl 44, which pawl is normally moved inwardly by means ofspring 46. Pawl 44 cooperates with a ratchet wheel 48, said wheel beinglocated within housing 42 and being immovably secured to a sleeve 50.The housing 42 and worm gear 40 may turn freely about the sleeve 50. Theinner end of lead screw I8 is received in sleeve 50, it being insertedin the sleeve as far as permitted by a collar 52 (see Fig. 1), and itbeing locked against rotation by suitable means such as the set screw54. This must not project, for the outside of sleeve 50 acts as a smoothor unthreaded part of the lead screw.

It will be evident from .inspection of the draw- 1 ings that the pawland ratchet wheel are so faced that the turntable normally drives thelead screw,-thus moving the cutting head gradually over the face of therecord from the outside toward the inside of the record. This producesthe desired sound track, and while the track is a spiral track, I shallin the present description limit the term spiralling to the finishingtrack. Thus, in Fig. l, the first lines of the soundtrack are indicatedat 56. The recording is not yet completed, and the last few lines to berecorded are indicated in broken lines at 58. When the recording isfinished, the cutting head is moved rapidly inward to produce the spiralfinishing track 60 which in turn leads directly to an extradeep circularfinishing groove 62. It is manifest that the spiral finishing track 60may be produced by rotating the lead screw I8 far more rapidly than itis normally driven by'the tumtable. It will also be understood that theoverrunning clutch, or pawl and ratchet mechanism, permits the leadscrew to be driven faster than the worm gear.

Lead screw I8 is rotatable in a car-' Appropriate means may, be providedtov drive the lead screwat the desired increased speed;

In the present case, this is done simply by means of a crank.v The crankis clearly'shown in Figs.

7 1 and 3, it comprising a handle 64 mounted on a crank disc 66. Thedisc 66 turns a shaft 68, the I inner end of which has means I0 keyingthe crank shaft tothe lead screw I8. In the present .case, the means I0is a pin or screw set' into the crank shaft and received in a mating"slot 12 cut radially at the endof 'thelead screw. Crank shaft 68 ispreferably rotatably receivedin a their usual advantages.

sleeve I4. The shaft is heldagainstaxial movement in sleeve by means ofthe disc 66 at the outer end, and the rear edge of cone bearing I6 atthe inner end. Cone bearing I6 is received within a conventionalcentering hole I8 atvthe outer end of the lead screw. The sleeve 14 isaxially slidable in the bearing 80 forming a part of the end or head 22of carrier arm 20. Referring to Figs. 1 and 5, it will be seen thatbearing 80 is provided witha thumb screw 82,.said

thumb screw being tightened against :thesl'eeve I4 in order to lock thesame inposition;

The use of cone bearings'is customary in these machines in order toinsure accurate centering of the lead screw andjto prevent end play.The, present arrangementretainscone bearings with Referring-to '3, theinner end of the lead screw. supported by cone bearing 84 which is heldin position by set screw 86. This cone bearing may, if desired, beformed on the handle 88 which is bestshown inFig. 1, I and which may beused when swingingthe carrier arm 20 away from the turntable.

For thispurpose the outer'end ofthejcarrier' arm is pivotally mounted onhorizontaltrunnions and'on a vertical bearing. Referring toFigs. 1 and5, it will be seen that bearing 80 is received in horizontal bearings 90in a'bearing yoke 92, the vertical spindle 94 of which is received in astationary bearing 96. With this arrangement, the inner endof thecarrier arm together with the driving flange'30 may be lifted and swunoutwardly to a point clear of the turntable. This is done when loadingthe turntable with a record,

and is also done when playing back a record, the

carrier arm- 20 being swung out of the way of the pick-up arm I00. Thispick-up arm is pivoted for vertical and horizontal'oscillationon asupport pedestal I02. Whennot in use, it is placed on a rest I04. Thefree end of the pickup arm carries a reproducing needle or stylus, saidneedle being'held in position by screw I06. The pick-up may be of anyconventional type.

In operation, the record 34 is placed on tumtable I2, and carrier arm 20is then positioned with flange 80 coupled to the turntable. The cuttinghead carrier I6 may be released from lead screw. I8 by depressing thefeed lever I08. As is best shown in Fig. 4, when feed lever I08 isdepressed, the inner end H0 is elevated and is thereby freed from thelead screw. When the cutting head has been lowered at a suitablestarting point near the beginning of the record, the feed lever I08 maybe released, thus engaging the carrier I8 with the lead screw. Thecarrier is, of course, swung downwardly to the position shown in Fig. 4in order to bring the cutting head into engagement with the record. Atthis time the arm I I2 extending rearwardly from the carrier bearsagainst the smooth, polished produce the spiral run-out groove GII.

strap II4,of the carrier rests over the upper tie rod 26, at which timethe cutting head is held out of engagement with the record. The cuttingpressure exerted by the cutting stylus .I I6 is controlled by a springN8, the tension of the spring being adjustable by means of an adjustingscrew I20.

After a few revolutions of the turntable, the

recording is begun and continues until completed,

When completed, the normal feed may be con- -tinued for another fewrevolutions, following which the crank 64 is turned by hand, therebyrapidly feeding the cutting head inwardly to Finally, the feed lever I03reaches the deep cut-away part or groove I22 at the inner end of thelead screw, whereupon continued rotation of the lead screw is withoutefiect. The cutting head remains stationary and produces the extra deepfinishing groove. 62. The fact that groove I22 on the lead screw iswider than the feed lever III8 is without consequence, for the cuttinghead moves along the carrier arm with a snug engagement and considerablefriction, and ceases movement the moment the propulsion by the leadscrew stops. In this respect the heavy cutting head with its associatedmechanism is quite different from the extremely light-weight and readilymoved pick-up arm. The sleeve 50 is smoothly finishedand is of the samediameter as the lead screw, so that it readily receives the inner one ofthe bearings I24 of the cutting head carrier.

I have so far spoken of the utility of the spiralling mechanism forproviding a run-out groove the end of a record. This mechanism may,however, be used for other purposes. For example, referring to Fig. 6,the record I is provided not only with a spiral run-out groove I32, butalso with a spiral startinggroove I34, This permits the record to bestarted by simply lowering the pick-up stylus on the marginal portion ofthe record, without attempting to locate it in the first sound groove.In less than one revolution of the turntable, the stylus reaches thestarting groove I34 and is thereby carried rapidly inwardly to the soundgrooves I36. The method of making the starting groove I34 will beobvious, the cutting head being started near the edge of the record, andthe spiralling crank 64 being turned until the cutting head has beenmoved inwardly an appreciable distance, whereupon normal feed is begunby simply discontinuing rotation of the crank. In Fig. '6 the groovesintermediate the first andlast few grooves have been omitted.

The spiralling mechanism may also be-used to provide connecting groovesbetween short recordings. Thus, referring to Fig. '1, the record I40 isprovided with a series of short recordings I42, I44 and I4. These areconnected by spiral tracks I48 and ISO. The recording I46 may also beprovided with spiral run-out track I52, The spiral tracks I43, I50 andI52 may each be used as a run-out and tripping groove. mentioned thatthe automatic stopping mechanisms provided on most phonographs are soarranged that the stopping point may be adjusted anywhere on the face ofthe record. The short recordings may, for example, be different soundeffects, or they maybe spot announcements. In such case, the operatorsimply adjusts the automatic tripping mechanism for whichever recordingis to be used. The spiral track at one side of the recording may be usedas a starting groove,

It may be and that on the opposite side may be used as a run-out andtripping groove.

It should be understood that while the description has so far assumedthat the record is cut and played from the outside in, it may also becut and played from the inside out. The latter procedure is preferred bymany. For this purpose, the lead screw is changed from lefthand asshown, to right-hand. One important advantage of the present simplifiedspiralling mechanism and the manner in which it interchangeably receivesany of a number of lead screws, is that the lead screw may be changedfrom left-hand to right-hand or vice versa, as well as changed in pitch.On 'this point, it will be observed that the lead screw is always turnedin one direction by the turntable, hence the crank is turned in only onedirection regardless of whether the recording is from the outside in orfrom the inside out More specifically, the turntable turns clockwise asviewed from above, and the lead screw turns clockwise as viewed from thecrank end. In this way the crank is turned in the most naturaldirection, that is, away from the operator at the top of the arc. Thesame unidirectionally driven clutch is applicable to either type of leadscrew.

One further use for the spiralling mechanism may be mentioned. This isthe possibility of somewhat increasing the pitch or spacing of the soundgrooves when reaching isolated extra-loud points in an otherwisemoderately loud recording. The sound grooves are very closely spacedwhen making the so-called long-playing records which may, for example,cover a period of fifteen minutes. With such records, the groove spacingmay be inadequate where the cutting stylus vibration is'of particularlygreat amplitude. It-has heretofore been necessary to cue the recordingwith the operatonwho would cut down the recording volume at theextra-loud points. This, of course, has the disadvantage that when therecording is reproduced, it does not faithfully reproduce theproportional loudness at those points. When using recording apparatusprovided with the present spiralling mechanism, the operator may followhis cues by cranking the lead screw somewhat at the loud points, therebyproviding a greatly increased spacing between sound grooves in a recordwhich otherwise has closely spaced sound grooves.

It is believed that the construction as well as the method of operationof my improved spiralling mechanism for sound recording apparatus,

and the many advantages thereof, will be apparent from the foregoingdetailed description thereof. The operator of the machine preliminarilyselects and inserts the proper lead screw, this being changed from timeto time depending, for example, upon whether the recording is to be oneten-inch record at '78 R. P. M. with considerable pitch, or is to be alarge-diameter long-playing record at 33 R. P. M. with small pitch. Forinstallations where the lead screw is changed frequently, each leadscrew preferably carries its own worm gear and clutch. To remove andreplace the lead screw, it is then merely necessary to loosen the thumbscrew 82; to then draw back the crank-disc 66 and with it the centerbearing 18, whereupon the lead screw with its gear and clutch is removedand another inserted. No tools are required, and the change may be madevery rapidly. In installations where the lead screw is changed onlyinfrequently, a single gear and clutch may be used, this beingtransferred from one lead screw' to -anotherbyloosening the set Ipreciableburden to provide'e'ach screw 54, Even; with": thisarrangement, the change may be madequite rapidly, and requires only a-'screw driver: However, the gear and clutch assembly isinexpensiv'e',"and-v it is no api'ts ownfgear and-clutch. It will beapparent that whileI have shown and lead screw with described the invention in a preferredform,

many changes and modifications maybe made in the structure disclosed,without departing from the spirit of the invention defined in thefollowing claims.

I claim:

1. Recording apparatus comprising aturnt able,

a cutting head, a lead screw for moving the cut ,ting head over theturntable, said lead screw terminating in a portion of reduced diameterfor letting the cutting head remain stationary in order to produceacircular track concentric with the record, means gearing the turntableto the lead screw, said means includingan overrunning clutch so facedthat the leadscrew maybe driven faster than it is driven bytheturntable, and ontionally'useable means to turn the lead screw at acomparatively rapid rate followingthe end of a a recording until thecutting head is moved to the reduced diameter portion at the end of thelead screw, whereby the record is provided with a spiral run-out grooveleading to a circular track".

2. Instantaneous recording apparatus comprising a'turntable, acuttinghead, a lead-screw for l moving the cutting head over theturntable, saidi lead s'crewj terminating in a portion of reduceddiameter for keeping the cutting head stationary 'in order to produce acomparatively deep circular track concentric with the record, meansgearing the tumtableto the lead screw,.s'aid means including pawl andratchet mechanism so faced that the lead screw may be driven faster thanit is driven by the turntable, and a manually rotatable crank tov turnthe lead screw at a comparatively rapid rate following the end of arecording until the cutting head is moved to the reduced diameterportion atthe end of the lead screw, whereby the record is provided witha spiral run-out groove I leading to-a circular track.

3. Recording apparatus comprising a turntable, a cutting head, aremovable and replaceable lead screw for moving the cutting head overthe turntable, said lead screw being selected to produce the desiredpitch for the sound track, means gearing the turntable to the leadscrew, said means including an overrunning clutch so faced 1 that thelead screw may be driven faster than it would normally be driven, by thetumtable, said/clutch detachably receiving one end of the leadscrew,.and optionally useable drive means detachably receiving theopposite end of the lead screw for turning the lead screw at acomparatively rapid rate.

4. Instantaneous recording apparatus comprising a turntable, a cuttinghead, a removable and replaceable lead screw for moving the cutting headover the turntable, said "lead screw having a pitch selectedtoproducethe desired number '5. Recording apparatus comprising a turntable, acutting head carrier arm' having a rotatable flange atits inner end forengaging the 7 center of a record carriedbythe turntable, said carrierarm being pivotally mounted at its outer end so that the arm maybeswun'gaway from the turntable, a removable and replaceable lead screwmounted on said carrier arm, a cutting head carried by said. leadscrew,aTvvorm driven by the aforesaid flange, a worm gear mes'hin'g withsaid worm, overrunning clutch mechanism associated with said worm gear,the overrunning part of the clutch detachably receiving the in ner endof the lead screw, the outer end of said carrier arm having abearingreceiving'a sleeve, releasable means for locking said sleevewithin said bearing, a crank shaft rotatable in but notaxially movablein said sleeve, a cone bearhead carried by the carrier arm and moved bymechanism mounted on said rotatable means and of lines per inch on therecord, means gearing the turntable to the ilead'screw, said meansincluding a pawlandratchetmeans so faced that;

the leadts'crew may-bedriven faster than itis driven. by the turntable,said means detachably receiving one end of the lead screw, and amanually'rotatable crank detachably connected to the opposite .end ofthe lead screw in order to turn the lead screwatza comparativelyrapidrate;

said lead screw, a .worm driven by the turntable, a worm gear meshingwith said worm, overrunning clutch mechanism associated with said wormgear, the overrunning part of the clutch mechanism receiving one end ofthe lead screw, the outer end of said carrier arm having a crank whichis also operatively connected to one end of thelead screw.

7. Recording apparatus comprising a turntable, a cutting head carrierarm having'a rotatable flange at its inner end for engaging the centerof a record carried by the turntable, a

removable and replaceable lead screw, assembly mounted on said carrierarm, said lead screw assembly including a lead screw, rotatable meansremovably receiving one end of th lead screw, a worm gear and associatedoverrunning clutch mechanism mounted on said rotatable means andconnecting the. worm gear to the lead screw, a worm driven by theaforesaid flange and meshing with said worm gear, a crank at the outerend of said carrier arm, and means detachably connecting said crank tosaid lead screw.

8. Recording apparatus comprising a turntable, a cutting head carrierarm having a ro tatable flange at its inner end for engaging the centerof a record carried by the turntable, a -removable and replaceable leadscrew assembly mounted on said carrier arm, said lead screw assemblyincluding a lead screw, rotatable means removably receiving one end ofthe lead screw, a worm gear and associated overrunning clutch connectingthe worm gear to the lead screw, a worm driven by the aforesaid flangeand meshing with said worm gear, the outer: end of'said carrierarmhaving'a crank shaft',-a crank at the outer end of said shaft, meansat the inner end of said shaft 'receiving'the end of the lead screw, andmeans whereby said-shaft is axially mov-' able to release the leadscrew.v

. v9.'Recording apparatus comprising a turntable, a cutting head carrierarm having-"a rotatable flange at its inner end for engaging the centerof a record carried by the turntable, a removable and replaceable leadscrew assembly mounted on said carrier arm, said lead screw assemblyincluding a lead screw having center holes at its ends, a hub removablysecured to one end of the lead screw, a worm gear and associatedoverrunning clutch mechanism mount ed on said hub and connecting theworm gear to the lead screw, a worm driven by the aforesaid flange andmeshing with said worm gear, center bearings at the ends of said carrierarm receiving said lead screw assembly, one of said center bearingsbeing axially movable for ready removal and replacement of the leadscrew assembly, a crank at the outer end of said carrier arm, and meansdetachably connecting said crank to said lead screw.

10. Recording apparatus comprising a turntable, a cutting head carrierarm having a rotatable flange at its inner end for engaging the centerof a record carried by the turntable, said carrier arm being pivotallymounted at its outer end so that the arm may be swung away from theturntable, a removable and replaceable lead screw assembly mounted onsaid carrier arm, said lead screw assembly including a lead screw havingcenter holes at its ends, a hub removably secured to one end of the leadscrew, and a worm gear and associated overrunning clutch mechanismmounted on said hub and connecting the worm gear to the lead screw, aworm driven'by the aforesaid flange and meshing with said worm gear, theinner end of said carrier arm having a fixed center bearing to receivethe inner end of the lead screw assembly, the outer end of said carrierarm having a crank shaft, the inner end of said crank shaft having acenter bearing to receive the outer end of the lead screw assembly, andhaving means to rotate the lead screw with the crank shaft, a crank atthe outer end of said crank shaft, a sleeve surrounding said crankshaft, said crank shaft being rotatable in but not axially movable insaid sleeve, and

means whereby the said sleeve is axially movable to release the leadscrew assembly from the center bearings.

11. Recording. apparatus comprising a turntable, a cutting head carrierarm having a rotat-- able flange at its inner end for engaging thecenter of a record carried by the turntable, a removable and replaceablelead screw mounted on said carrier arm, a worm gear rotatably mounted atthe inner end of the carrier arm, overrunning clutch mechanismconnecting said worm gear to said lead screw, a worm driven-bythe.aforesaid flange and driving said worm gear, the inner end of saidcarrier arm having bearing means for the worm gear and lead screwassembly, the outer end of said carrier arm having a crank shaft, meansdetachably connecting the crank shaft to the lead screw, a crank at theouter end of said shaft, said shaft being axially slidable at the outerend of the carrier arm, and a manually releasable means for locking saidshaft in desired axial position.

12. Recording apparatus comprising a turntable, a cutting head carrierarm having a rotatable flange at its inner end for engaging the centerof a record carried by the turntable, a re-- movable and replaceablelead screw assembly mounted on said carrier arm, said lead screwassembly including a lead screw having center holes at its ends, a wormgear rotatably mounted on one end of said lead screw, overrunning clutchmechanism connecting said worm gear to said lead screw, a worm driven bythe aforesaid flange and driving said worm gear, a crank at the outerend of said carrier arm, and cone center bearings at the ends of saidcarrier arm receiving said lead screw assembly, one of said centerbearings being axially movable for ready removal and replacement of thelead screw assembly.

13. Recording apparatus comprising a turntable, a cutting head carrierarm having a rotatable flange at its inner end-for engaging the centerof a record carried by the turntable, a removable and replaceable leadscrew assembly mounted on said carrier arm, said lead screw assemblyincluding a lead screw having center holes at its ends, a'worm gearrotatably mounted on one end of the lead screw, overrunning clutchmechanism connecting said worm gear to said lead screw, a worm driven bythe aforesaid flange and driving said worm gear, the inner-end of saidcarrier arm having a fixed center bearing, the outer end 'of saidcarrier arm having an axially movable center bearing, said centerbearing being formed at the inner end of a crank shaft, a crank at theouter end of said shaft, a sleeve surrounding said shaft, said shaftbeing rotatable in but not axially movable in said sleeve, said sleevebeing axially slidable in a bearing at the outer end of the carrier arm,and a manually rotatable thumb screw for locking said sleeve in desiredaxial position.

14. Recording apparatus comprising a turntable, a carrier arm havingmeans at its inner end for engaging the center of the turntable, saidcarrier arm being pivotally mounted at its outer end so that the arm maybe-swung away from the turntable, a removable lead screw mounted on saidcarrier arm, a cutting head mounted on said carrier arm and arranged tobe moved by said lead screw, a worm driven by the turntable, a

a worm gear meshing with said worm, overrunning clutch mechanismassociated with said worm gear, the overrunning part of the clutchmechanism receiving one end of the lead screw, for normal slow speedoperation of the lead screw, and a crank operatively connected to thelead screw and adapted by convenient manual operation to turn the leadscrew faster than its normal drive speed in order to produce a spiralgroove of high pitch when desired.

j 15. Recording apparatus comprising a tumtable, a carrier arm, aremovable lead screw mounted on said carrier arm, said lead screw havingcenter holes at its ends, a gear at one end of the lead screw so mountedas to be rotatable relatively thereto, overrunning clutch mechanismconnecting said gear to said lead screw, means driven by the turntablefor driving said gear, an additional independent drive means coupled tosaid lead screw for rotating the lead screw faster than its normal speedin orderto produce a spiral groove of high pitch when desired, and conecenter bearings at the ends of said carrier arm for receiving said leadscrew, one of said cone center bearings being axially movable for readyremoval of the lead screw.

16. Recording apparatus comprising a turntable, a cutting head, aremovable and replaceable lead screw for moving the cutting head overthe turntable, said lead screw being selected to produce the desireddirection and pitch for the sound track, means gearing the turntable tothe lead screw for normal drive of the lead'screw, said means includinga worm and worm gear with the worm being driven by the turntable andoperating to drive the worm gear, an additional optionally-usable drivemeans detachably receiving the lead screw and adapted to be operated athigher speed than the normal drive for the lead screw, and slip means inthe gearing betweenthe worm gear and the lead screw. in order to afiordoverrunning movement of the lead screw relative, to the worm-gear, saidslip means being adequate to feed the cutting head under drive of theturntable, the additional optionally-usable drive 1 means when operatedat higher speed as aforesaid functioning to turn the leadscrew muchfaster than it is normally driven by the turntable in order to produce aspiral groove of high pitch.

17. Recording apparatus comprising a turning the turntable to the leadscrew for normal slow-speed operation of the lead screw, said meansincluding a wormand worm gear with the worm being driven by theturntable and operating to drive the worm gear, optionally usablerotatable means detachably receiving the lead screw, said rotatablemeans including a manually operable crank which may be readilyandconveniently used for turning the lead screw faster than it is normallydriven by the turntable in order to produce a spiral groove of highpitch when desired, slip means in the gearing between table, a cuttinghead, a removable lead screw ar- ;ranged to be positioned over theturntable for: moving the cutting head thereover, means gearthe wormgear and the lead screw in order to afford overrunning movement of thelead screw relative to the worm gear, said slip means; being

